Losmandy GM811G Equatorial Mount with Gemini 2 GOTO and HD Tripod

Product Overview

This is the Losmandy GM811G supplied on the folding heavy-duty tripod rather than the lightweight one. The mount pairs a G11-size RA axis with a GM8-size DEC axis and ships with the Gemini 2 GOTO servo system, a counterweight shaft and one 11 lb counterweight. Losmandy publishes an instrument capacity of 50 lb for imaging and 65 lb for visual use on a 26 lb equatorial head; the HD tripod itself is rated to carry up to 425 lb and weighs 35 lb.

Who It's For

This is a good match if you want the GM811G's mixed-axis design on the most stable support Losmandy makes for it. The heavy-duty tripod is the right choice for a fixed observing pad, a long tube that needs the extra leg spread, or simply an observer who would rather over-support the mount than find the limit. If you carry your mount to a site regularly, the lightweight-tripod version of the same mount is the lighter proposition.

Key Features & Design

• 50 lb imaging / 65 lb visual instrument capacity on a 26 lb equatorial head.
• G11-size RA gear: 5.625 inches, 360 teeth, 7075 aluminium — the same RA gear as the G11G.
• GM8-size DEC gear: 2.812 inches, 180 teeth, 7075 aluminium.
• Spring-loaded worm for adjustment-free tracking, dual supported and ball-bearing housed, ground high-precision brass.
• ±5 arcsecond or better uncorrected tracking, corrected periodic error often ±2.5 arcseconds or better, with built-in permanent periodic error correction.
• Gemini 2 GOTO: DC servo motor based computerised positioning, accuracy published at up to half an arcminute.
• Folding HD tripod: adjustable legs from 33" to 52", 29" between legs when retracted but spread, folds to 14" x 14" x 39", carries up to 425 lb, 35 lb.
• Supports altitudes from 0° to 68°, and runs on 12–18 V DC.

Mechanical Design

The GM811G's design point is that RA and DEC do different amounts of work. RA turns continuously through an exposure, so periodic error there shows up in the stars; DEC barely moves once the target is acquired. Losmandy fits the 5.625-inch, 360-tooth G11 gear to RA and the 2.812-inch, 180-tooth GM8 gear to DEC, keeping the tracking-critical axis at G11 standard while holding the head to 26 lb.

The spring-loaded worm maintains its own mesh, so there is no worm adjustment in normal use. On this configuration the support is the folding heavy-duty tripod: adjustable from 33" to 52", 29" between leg centres when retracted but spread, and rated to 425 lb — far beyond what this head will ever ask of it, which is the point of specifying it.

Recommended Uses

Deep-sky imaging with a mid-size refractor or astrograph inside the 50 lb imaging rating, from a fixed pad or a regular observing position. Visual observing up to the 65 lb rating. Long tubes where the wider leg spread and stiffer legs help. Remote or automated sessions through Gemini 2. Installations that may later move onto a permanent pier.

Compatibility and Accessory Notes

Saddle: accepts both Losmandy D-series and Vixen-style V-series dovetail plates. We stock the D-series universal plates and the V-series plates.

Counterweights: one 11 lb weight is included, with 7, 11 and 21 lb sizes available separately.

Tripod accessories: we stock the large-diameter vibration pads for the HD tripod legs, the lever-type leg clamp set, and tripod extensions in 4", 8" and 12" lengths.

Pier: the MA tripod/pier adapter fits this mount and also sits on permanent piers.

Polar alignment: the iPolar electronic polar scope or the optical polar scope with illuminator.

Good to Know Before You Order

The HD tripod is 35 lb on its own. With a 26 lb head and an 11 lb counterweight this is a two-trip setup. If portability matters more than stiffness, the lightweight-tripod version of the same mount is the one to look at.

The two axes are different sizes by design. Consumables come in mixed sets accordingly — the GM811 clutch pad set carries one GM8-size and one G11-size pad.

Tracking figures are Losmandy's published specifications. Balance, polar alignment and seeing all bear on the result.

Published altitude range is 0° to 68°.

Frequently Asked Questions

Is it difficult to set up?

No. Tripod down, head on, shaft and counterweight, balance, polar align. The spring-loaded worm means no mesh adjustment to learn, and Gemini 2 handles pointing from its hand controller.

What do I gain over the lightweight-tripod version?

Stiffness and leg spread. The HD tripod is rated to 425 lb, spreads 29" between leg centres and weighs 35 lb. It is the better support and the heavier one; the mount head and its specifications are identical.

Why are the RA and DEC axes different sizes?

RA does the tracking during an exposure and DEC does not, so the large G11 gear goes where it affects the image and the smaller GM8 gear where it does not.

Does it need a computer?

No. Gemini 2 runs as a self-contained GOTO system from its hand controller.

Bottom Line

The GM811G's G11 RA gear and 50 lb imaging capacity on Losmandy's 425 lb-rated folding HD tripod. The more stable of the two GM811G configurations, and the heavier one to move.